For information about oversized valves & seats see section on "additional
product information"

These are special alloy* racing seats for all 8-valve twinspark engines that
convert to 46 or 47mm intake valves.

*Modified M2 Tool Steel, which utilizes a blend of three types of carbide
materials to provide outstanding wear resistance for valve seat insert
application. Molybdenum and Tungsten carbides are both harder and more
thermally stable than chromium carbides. They also form a carbide
structure to impart more stability to the base material. Vanadium carbides
are also added to provide greater wear resistance without affecting the
machineability of the product. This Iron based insert allows for excellent
heat transfer. T-series hardness run @ 42 Rc and is currently the industry
choice when mated with premium or Inconel valves.